1. Field of the Invention
The present invention relates generally to detecting structural changes of internal anatomical tissue and, more particularly, to devices for being implanted in the body to indicate of structural changes of internal anatomical tissue and to systems and methods therefor.
2. Description of the Prior Art
Many various conditions and diseases cause internal anatomical tissue including organ structure to undergo various structural changes such as changes in size, configuration, consistency and density. Many structural changes of internal anatomical tissue are indicative of disease and/or the need for treatment; however, the internal location of the structural changes within the body makes early detection extremely difficult. One area in which structural changes of tissue occurs involves cervical changes during pregnancy. The cervix, which consists primarily of fibrous tissue and smooth muscle, acts as a form of sphincter adaptable in size and shape to accommodate passage of a baby from the uterus into the vagina during childbirth. During pregnancy, the cervix undergoes various changes in preparation for childbirth including cervical effacement wherein the wall forming the cervix thins out and shortens and dilatation wherein the diametric or lateral size of the cervical canal is increased to accommodate passage of the baby.
Many pregnancy patients mistake normal sensations of pregnancy, such as the sensations associated with the baby kicking and moving, for labor pains or contractions. Patients who perceive that they are in labor typically seek medical intervention from physicians and hospitals unnecessarily since they do not know that true labor has not begun. On the other hand, many other pregnancy patients who are in labor may not realize that they are in labor and may fail to timely seek medical attention. The inability of pregnancy patients to detect when cervical changes have occurred and, therefore, to know when labor has begun or is near, gives rise to various communication problems between doctors and patients, increases medical costs and inefficiencies and creates unnecessary patient anxiety.
Occasionally, cervical effacement and dilatation occur prematurely with resulting miscarriage or premature birth. When premature cervical effacement is detected early, preventative measures can be taken to avoid miscarriage and premature delivery and to prolong pregnancy. For example, a suture stitch can be tied like a purse string around the cervix to keep the cervix closed. The suture is left in place until the pregnancy is at or near full term at which time the suture is cut to allow normal delivery of the baby. The success of preventative measures to prolong pregnancy depends on early detection of cervical effacement; however, patients typically do not know when cervical effacement has occurred. Accordingly, such patients may not seek medical attention until after obvious symptoms have occurred, at which time the cervical changes may have progressed to a point where miscarriage or premature delivery cannot be prevented.
Another area in which structural changes of internal tissue occurs involves tumors. In many cases, it is desirable to monitor tumors to detect an increase in size and/or to establish a pattern of growth for diagnostic and/or treatment purposes. Depending on the nature of the tumors or the location of the tumors in the body, monitoring may be difficult and inaccurate even with the use of sophisticated equipment. Additionally, in many instances, changes in tumors are identifiable only with specific medical tests such that significant changes may have already occurred by the time the tests are performed.
Accordingly, there is a great need for a safe, implantable device for indicating structural changes of internal anatomical tissue to allow such changes to be detected as soon as possible after they have occurred.